全文获取类型
收费全文 | 529篇 |
免费 | 23篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 244篇 |
金属工艺 | 9篇 |
机械仪表 | 6篇 |
建筑科学 | 18篇 |
矿业工程 | 2篇 |
能源动力 | 4篇 |
轻工业 | 72篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 18篇 |
一般工业技术 | 98篇 |
冶金工业 | 21篇 |
原子能技术 | 3篇 |
自动化技术 | 50篇 |
出版年
2023年 | 12篇 |
2022年 | 72篇 |
2021年 | 64篇 |
2020年 | 28篇 |
2019年 | 16篇 |
2018年 | 21篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 21篇 |
2014年 | 19篇 |
2013年 | 34篇 |
2012年 | 26篇 |
2011年 | 45篇 |
2010年 | 22篇 |
2009年 | 16篇 |
2008年 | 23篇 |
2007年 | 17篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 10篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1968年 | 1篇 |
排序方式: 共有552条查询结果,搜索用时 31 毫秒
491.
Camilla Della Torre Ilaria Corsi Maria Maddalena Dinardo Luigi Alcaro Angelo Tursi Antonio Frigeri 《The Science of the total environment》2010,408(9):2136-2145
The aim of the present study was to evaluate the environmental threat to benthic species from chemical weapons dumped in the southern Adriatic Sea. An ecotoxicological approach using chemical analysis and biological responses was applied, in two sentinel species: the Blackbelly rosefish Helicolenus dactylopterus and European conger Conger conger. Specimen were collected in a stretch of sea, where had been dumped war materials and from a reference site free of ordnance. Residues of yperite, Hg and As were measured in fish fillets. Skin, liver, kidney and spleen were examined for histopathological and macroscopical lesions. Liver detoxifying capacities (EROD and UDPGT) and genotoxicity (comet assay) were also investigated. As and Hg levels were three-four times higher than those from the reference site in both species (p < 0.001). Both species captured in dumping site showed clear signs of chronic illness according to the health assessment index (HAI). Deep ulcers and nodules were observed on skin and external organs. Histological lesions such as periportal and bile duct fibrosis, pericholangitis, steatosis, granuloma and elevated splenic MMCs were detected in liver and spleen. Significantly higher EROD activities were also found in both species from dumping site (p < 0.01). Comet assay revealed genotoxicty in gills of C. conger from dumping site, indicating uptake of chemical warfare agents through fish gills. European conger was found to be a more sensitive bioindicator of this type of contamination than the Blackbelly rosefish. 相似文献
492.
Giovanni Ravazzani Ilaria Giudici Christian Schmidt Marco Mancini 《Canadian Metallurgical Quarterly》2011,137(8):564-571
Population growth coupled with industrialization, increasing effects of climate change, and increasingly stringent water management regulations regarding the conservation of aquatic life are resulting in previously unknown agricultural water shortages in Padana Valley, Italy. To mitigate water shortage, it was recently proposed to use the water stored into numerous quarries of gravel material. Because quarry lakes are mostly located in the proximity of watercourses, aquifer drawdown induced by pumping can affect flow in nearby streams. The evaluation of the potential of quarry lakes for supplemental irrigation has to face stream depletion that is crucial from the perspective of the legal rights of the downstream users and ecosystem sustainability. The work presented in this paper investigates the potential of a quarry lake in Padana Valley to sustain irrigated crop water requirement during shortage periods. A simple and quite inexpensive technique for assessing streambed conductance based on streambed temperature measurements is presented. The results show that quarry lakes may be a promising alternative resource for supplemental irrigation during shortage periods, even when a watercourse is present in the surrounding area. 相似文献
493.
Silvia Rinaldi Elena Fortunati Marco Taddei Josè M. Kenny Ilaria Armentano Loredana Latterini 《应用聚合物科学杂志》2013,130(2):1185-1193
Biodegradable polymer based nanocomposite materials have attracted much attention since they can be used for biomedical and pharmaceutical applications. In order to have highly integrated PLGA nanocomposite materials, silver colloidal nanoparticles were prepared in chloroform starting from silver nitrate and using polyvinylpyrrolidone as reduction and capping agent. TEM and AFM imaging give information on the size distribution of the silver nucleus (7.0 nm) and the capping shell (8.2–10.7 nm). PLGA–Ag nanocomposites were prepared upon addition of 1 or 3% wt of silver nanoparticles to the PLGA/chloroform suspension. The effect of silver loading on polymer degradation was studied following the mass loss and the morphology of nanocomposite films at different degradation stages. The concentrations of Ag+, which is released during nanocomposite degradation, were monitored and analyzed through the diffusion model, to have insight on the degradation kinetics. The release rate, and likely the degradation rate, was reduced at higher silver loading. Bacterial growth tests indicated that the cell growth is inhibited in the presence of PLGA–Ag nanocomposites and the efficiency is correlated to Ag+ release. Thus, controlling the nanoparticle loading, a tunable degradation and antibacterial action can be designed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1185‐1193, 2013 相似文献
494.
TREND OF ATMOSPHERIC BENZO[ a ]PYRENE IN ITALY BEFORE THE ADOPTION OF THE EUROPEAN DIRECTIVE ON PAHs
Edoardo Menichini Vito Belladonna Franca Bergoglio Claudio Gabrieli Marcello Ceccanti Ilaria Rossi 《Polycyclic Aromatic Compounds》2013,33(2):79-92
The benzo[a]pyrene temporal trend was investigated in 11 towns where at least five annual means were available. The overall number of stations was 22, of which 12 were traffic-oriented, 6 background and 4 industrial. The trend was generally declining at traffic-oriented sites and roughly stable at background sites. The annual means in 2004 still exceeded the forthcoming European target value of 1 ng/m 3 in two towns (up to 1.9 ng/m 3 ). The background means (up to 1.4 ng/m 3 in 2004) accounted for approximately 40–90% of those at the traffic-oriented sites in the same town. The presence of a coke plant was incompatible with the attainment of the target value, while the adoption of technical measures on a carbon electrode plant was successful in attaining concentrations lower than the target value. In heavy traffic areas in Italy, the attainment of the target value hardly appears feasible under the current conditions of traffic congestion. 相似文献
495.
Katherine E. Jolley Antonio Zanotti‐Gerosa Fred Hancock Alan Dyke Damian M. Grainger Jonathan A. Medlock Hans G. Nedden Jacques J. M. Le Paih Stephen J. Roseblade Andreas Seger Vilvanathan Sivakumar Ivan Prokes David J. Morris Martin Wills 《Advanced Synthesis \u0026amp; Catalysis》2012,354(13):2545-2555
An improved method for the synthesis of tethered ruthenium(II) complexes of monosulfonylated diamines is described, together with their application to the hydrogenation of ketones and aldehydes. The complexes were applied directly, in their chloride form, to asymmetric ketone hydrogenation, to give products in excess of 99% ee in the best cases, using 30 bar of hydrogen at 60 °C, and to the selective reduction of aldehydes over other functional groups. 相似文献
496.
Martin D’Agostino Nigel Cook Ilaria Di Bartolo Franco M. Ruggeri Alessandra Berto Francesca Martelli Malcolm Banks Petra Vasickova Petr Kralik Ivo Pavlik Petros Kokkinos Apostolos Vantarakis Kirsi S?derberg Leena Maunula Katharina Verhaelen Saskia Rutjes Ana Maria de Roda Husman Renate Hakze Wim Van der Poel Agnieszka Kaupke Iwona Kozyra Artur Rze?utka Jasna Prodanov Sava Lazic Tamas Petrovic Anna Carratala Rosina Gironés Marta Diez-Valcarce Marta Hernandez David Rodriguez-Lazaro 《Food Analytical Methods》2012,5(1):1-7
The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5?×?102 and 5?×?104?PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow. 相似文献
497.
Marotti I Bregola V Aloisio I Di Gioia D Bosi S Di Silvestro R Quinn R Dinelli G 《Journal of the science of food and agriculture》2012,92(10):2133-2140
BACKGROUND: Wheat grains are a rich source of dietary fibres, particularly in the western human diet. Many of the health effects attributed to dietary fibres are believed to be related to their microbial fermentation in the gut. This study evaluated the ability of two potentially probiotic strains, Lactobacillus plantarum L12 and Bifidobacterium pseudocatenulatum B7003, to ferment soluble dietary fibres (SDFs) from modern and ancient durum‐type wheat grains. RESULTS: Fibre microbial utilisation was highly variable and dependent on the strain. SDFs from the varieties Svevo and Solex supported the growth of L. plantarum L12 the best, whereas those from the varieties Anco Marzio, Solex and Kamut® Khorasan were good carbohydrate substrates for B. pseudocatenulatum B7003. The highest prebiotic activity scores (describing the extent to which prebiotics support selective growth of probiotics) for B7003 were obtained with SDFs from the varieties Solex (0.57), Kamut® Khorasan (0.56) and Iride (0.55), whereas for L12 the highest scores were achieved with the varieties Orobel (0.63), Kamut® Khorasan (0.56) and Solex (0.53). CONCLUSION: The present study has identified some SDFs from durum‐type wheat grains as suitable prebiotic substrates for the selective proliferation of B. pseudocatenulatum B7003 and L. plantarum L12 in vitro. The results provide the basis for the potential utilisation of wheat‐based prebiotics as a component of synbiotic formulations. Copyright © 2012 Society of Chemical Industry 相似文献
498.
Silvia Paterlini Riccardo Panelli Laura Gioiosa Stefano Parmigiani Paolo Franceschini Ilaria Bertocchi Alessandra Oberto Alessandro Bartolomucci Carola Eva Paola Palanza 《International journal of molecular sciences》2021,22(16)
NPY and its Y1 cognate receptor (Y1R) have been shown to be involved in the regulation of stress, anxiety, depression and energy homeostasis. We previously demonstrated that conditional knockout of Npy1r gene in the excitatory neurons of the forebrain of adolescent male mice (Npy1rrfb mice) decreased body weight growth and adipose tissue and increased anxiety. In the present study, we used the same conditional system to examine whether the targeted disruption of the Npy1r gene in limbic areas might affect susceptibility to obesity and associated disorders during adulthood in response to a 3-week high-fat diet (HFD) regimen. We demonstrated that following HFD exposure, Npy1rrfb male mice showed increased body weight, visceral adipose tissue, and blood glucose levels, hyperphagia and a dysregulation of calory intake as compared to control Npy1r2lox mice. These results suggest that low expression of Npy1r in limbic areas impairs habituation to high caloric food and causes high susceptibility to diet-induced obesity and glucose intolerance in male mice, uncovering a specific contribution of the limbic Npy1r gene in the dysregulation of the eating/satiety balance. 相似文献
499.
Giacomo Lazzarino Romina Pallisco Gabriele Bilotta Ilaria Listorti Renata Mangione Miriam Wissam Saab Giuseppe Caruso Angela Maria Amorini Maria Violetta Brundo Giuseppe Lazzarino Barbara Tavazzi Pasquale Bilotta 《International journal of molecular sciences》2021,22(16)
Nearly 40–50% of infertility problems are estimated to be of female origin. Previous studies dedicated to the analysis of metabolites in follicular fluid (FF) produced contrasting results, although some valuable indexes capable to discriminate control groups (CTRL) from infertile females (IF) and correlate with outcome measures of assisted reproduction techniques were in some instances found. In this study, we analyzed in blind FF of 35 control subjects (CTRL = patients in which inability to obtain pregnancy was exclusively due to a male factor) and 145 IF (affected by: endometriosis, n = 19; polycystic ovary syndrome, n = 14; age-related reduced ovarian reserve, n = 58; reduced ovarian reserve, n = 29; unexplained infertility, n = 14; genetic infertility, n = 11) to determine concentrations of 55 water- and fat-soluble low molecular weight compounds (antioxidants, oxidative/nitrosative stress-related compounds, purines, pyrimidines, energy-related metabolites, and amino acids). Results evidenced that 27/55 of them had significantly different values in IF with respect to those measured in CTRL. The metabolic pattern of these potential biomarkers of infertility was cumulated (in both CTRL and IF) into a Biomarker Score index (incorporating the metabolic anomalies of FF), that fully discriminated CTRL (mean Biomarker Score value = 4.00 ± 2.30) from IF (mean Biomarker Score value = 14.88 ± 3.09, p < 0.001). The Biomarker Score values were significantly higher than those of CTRL in each of the six subgroups of IF. Posterior probability curves and ROC curve indicated that values of the Biomarker Score clustered CTRL and IF into two distinct groups, based on the individual FF metabolic profile. Furthermore, Biomarker Score values correlated with outcome measures of ovarian stimulation, in vitro fertilization, number and quality of blastocysts, clinical pregnancy, and healthy offspring. These results strongly suggest that the biochemical quality of FF deeply influences not only the effectiveness of IVF procedures but also the following embryonic development up to healthy newborns. The targeted metabolomic analysis of FF (using empowered Redox Energy Test) and the subsequent calculation of the Biomarker Score evidenced a set of 27 low molecular weight infertility biomarkers potentially useful in the laboratory managing of female infertility and to predict the success of assisted reproduction techniques. 相似文献
500.
The study on the instability of gate contacts of Al/Ni gate AlGaAs/GaAs HEMT's was performed by means of storage tests carried out at three different temperatures: 200°C, 240°C and 300°C. Data from tests as long as 5000 hours were analyzed. At the highest temperature the main failure mode was the reaction between the Al of the gate electrode and the Au of the metallization. At 200°C, 240°C an increase of the barrier height was detected. The activation energy determined and the comparison with the data existing in literature is reported. 相似文献